So, I'm really not impressed by a lot of this.
Circle of the Shepherd
This is essentially the exact same as the previous version. The differences include: They learn Sylvan now, they can move the aura as a bonus action, Their summoned creatures are healed if they are in the aura, wolf aura is now unicorn aura, hawk aura is reworded.
And, Hawk is an aura I'd like to talk about. Once per short rest, you create this aura. Then, you can use your reaction to give someone advantage on an attack against a single creature in that aura.
That's... it? It could be useful I suppose, but that has got to be an enemy worth hitting to use it.
Then Bear, well, until 10th level when you can heal your summoned creatures the only use for bear is Temp hp. Otherwise advantage on strength checks and saves... well I guess saves come up kind of often, but checks? Not really worth using something that is once per short rest instead of just using the help action.
Unicorn is actually pretty decent, because you can heal everyone in the aura when you cast a healing spell. In fact, that one is so good it seriously makes you wonder why you would bother with the other two.
Let's say level 10: You could use bear to give some members of your party 15 temp hp, and then move an aura of advantage on strength. Or, you could have a movable aura that heals 10 hp every time you use healing word or cure wounds... or you could give up your reaction to give advantage to one attack per round...
And this druid again relies very heavily on summoning creatures to fight for it, which is not an easy build to run in 5e. Conjure Animals works because it is only an action, but most of the summoning spells take a minute to cast and only last for an hour, making them hard to pull off in a meaningful way. Can't summon them while traveling, because they could dissipate before you get to the fight, but can't summon them during the fight because they take too long to summon, so you need to summon them a little bit before the fight, while you are safe and aware a fight is going to take place soon. Not an easy balance to strike I've found.
Cavalier
There aren't many changes to this one either. You learn fewer skills with Bonus Proficiency. It used to be 2 skills, now it is 1 skill. Born to the Saddle only works if you fall less than 10 ft. Warding Manuever is new.
Everything else is the exact same, and has all the problems that come with it.
The question of "why not play a battlemaster" haunts this entire subclass. Trip attack and Precision Attack are already Battlemaster tricks, I can't find any use for Control Mount... because I can't find any rules for when you would need to make that roll anyways.
The only rules I can find for Mounted Combat boil down to how to mount a creature, how to get knocked off a creature, and if it is not an intelligent creature it is essentially just a way to change your movement speed.
So... This class can get on a mount faster (which is useless if you are just going to be using the mounts speed anyways) and can land on their feet if knocked off. Yay?
Other than aesthetics, why would you want to be on a mount in the first place? I guess it allows someone to have the mount disengage and move, so they are running through the enemies and striking them before getting out of range. But, this class doesn't make you better at that.
Now, all that griping aside, I really like Warding Maneuver. That is a cool ability. But, I really am just going to take that ability and give it to the battle master list anyways, because nothing else in the Cavalier is worth having.
Oath of Conquest
Now, this is some interesting new stuff. The fluff is the same, which is causing problems for some people I'm sure, but everything else is pretty cool.
I kind of wish it had more ways to grant fear. The fear spell hits a cone, and their channel divinity is on a short rest. Wait, Wrathful Smite gives fear. So, that should work pretty well then for giving plenty of ways to activate their Aura, which is just kind of brutal. Speed of 0, so you can't run away, and pyschic damage every turn.
I can see a high level Conquest Paladin walk into the middle of an enemy group, channel divinity fear. Every creature within 30 ft makes checks against the fear. Fail, and you are stuck cowering and taking damage. Succeed and run up to hit him? Take psychic damage, then damage from Armor of Agathys. Then he may deign you worthy of wetting his blade.
Frankly, it is much better designed and much cooler. Now all I need to do is play around with the oaths until I have some oaths that match up with characters that would work in a game and this thing is all set for play.
Undying Light
So, this one is much the same as it's previous incarnation, but they shuffled around a lot of the abilities and gave them a dice pool of healing. It works well enough now and is kind of interesting. A different take on the divine champion, now you just have to rework some of the better spells and abilities to make sense for a good aligned warlock.
As for the invocations, I did not notice how hugely limited Ghostly Gaze is. Yeah, that needs to be concentration for a minute or something similar. It isn't a combat ability so six seconds is way too short. And I hope a lot of the other invocations are still in the new book, some of them were really cool effects.
I'm not sure I like limiting them based on pact though. Why does the Chainlock get the improved healing for instance, and why can't my bladelock never sleep.